A new joint report by NTI and the Russian-based Center for Energy and Security Studies highlights key projects the United States and Russia can take on to innovate and build trust in the nuclear sphere.

Robert Wood, U.S. envoy to the U.N. nuclear watchdog, charged that Syria was attempting to remove all traces of past atomic work from the facilities in question.

The Assad regime's "own destabilizing actions are no justification for its refusal" to ignore its obligations as a signatory to the Nuclear Nonproliferation Treaty, Wood said in released remarks from an IAEA Board of Governors meeting.

"The Assad regime is using its brutal repression of the Syrian people as an excuse for not cooperating with the agency's investigation," the U.S. diplomat said in reference to the government's efforts to crush the rebellion that began last year.

The Vienna, Austria-based nuclear agency said in 2011 that Syria's Dair Alzour facility "very likely" previously contained a partially constructed reactor intended for plutonium production. The site was pulverized in a 2007 Israeli bombing.

Agency monitors in 2008 discovered traces of anthropogenic natural uranium at Dair Alzour. They have not been allowed to return to the razed site, while the agency has also sought data about another three facilities that might have connections to Dair Alzour.

"Syria must allow access to all relevant locations, materials and persons, including in particular the three additional sites suspected of having a functional relationship to the clandestine Dair Alzour," Wood said.

Syrian envoy Bassam al-Sabbagh reaffirmed Damascus' stance that there was no atomic operation at Dair Alzour. The diplomat said his government and the International Atomic Energy Agency in October 2011 reached a compromise to make the situation clear. There is no cause for worry about the other three sites if Dair Alzour can be proven to be strictly nonatomic in nature, according to al-Sabbagh.

Yukiya Amano, IAEA chief, appeared to dispute that claim in his Monday statement to the board.

"I wish to make clear that no agreement was ever reached on a so-called action plan," he said.

The organizations considered and ultimately dismissed "some options" raised during 2011 talks in the Syrian capital, according to Amano.

"It was not sufficient because the so-called action plan is limited only to the Dair Alzour site and Syria was not ready to discuss other locations," he said.